The urgent need to improve big city schools has been a powerful incentive to adopt accountability systems. The following types of accountability systems may exist alongside each other: (1) political; (2) legal; (3) bureaucratic; (4) professional; and (5) market. Bureaucratic accountability is a "top down" system that holds teachers responsible for following standard procedures. Professional accountability is "teacher focused" and emphasizes teacher preparation, certification, selection, and evaluation. Market accountability is based on "customer choice" that makes schools accountable to parents and students. Because each form has its own strengths and weaknesses, an effective system of accountability should combine several to ensure that students are well served. Statistical indicators play a major role in accountability systems. The following criteria should be considered in selecting indicators: (1) problem-oriented; (2) relevant to policy; (3) reflective of educational outcomes; (4) indicative of student backgrounds; and (5) illustrative of school context. The following criteria should be used in interpreting indicators: (1) validity; (2) reliability; and (3) corruptibility. Indicators should go beyond the traditional student standardized test scores to reflect factors that structure the student's experience of school. Properly conceived indicators can be used as powerful political tools and as incentives to change behavior. A list of 11 references is appended. (FMW)